Tdi 300 overheating problems/mystery

[clankilpatrick]

Good evening All,
Am writing this with the very real possibility firmly in the back of the mind that I cooked the motor in my 130 this evening . Will know for sure tomorrow morning when i can have a good look at it.
BUT in the mean time I am hoping somebody may be able to shed some light on what may be causing the overheating problems. :confused:
Up until this week I have had no problem at all with overheating but on the way to work the other day the little black box alarm went off and I noticed the temp gauge was getting hot. This was just after I had taken off again after being stopped at a red light for roadworks. I pulled over and let the vehicle cool for awhile and everything seemed fine so continued off on my way to work. The gauage actually dropped back to normal temp as I watched it as I was driving along. It happened again a couple of days later in exactly the same fashion ie driving for 20 mins, engine temp normal, pulled up at traffic lights, turned motor off, 5 minute wait, restart engine, take off and after short period the engine overheats again. This time had a longer wait until the temp dropped back enough so that I could get to work. On both occasions the temp was fine all the way home after work as well as driving around to and from work on the days in between.
I checked the wiring to the temp sensor and it was fine so a possible faulty thermstat was diagnosed as the potential cause. Drove 50 km out to a mates today to use his hoist as I thought may as well do the oil change at the same time as we changed the thermostst. No overhaeting problems and it was a bloody hot dry day!! Put a brand new LR thermostat in, topped up with coolant and did 2 test drives with heater on, and pushing it hard in 4th to try and get the engine temp hot. Did not budge past half way. problem solved, job done!! or so we thought. Took off home and was doing well but had to pull up after about 20 minutes at a stop sign on a railway crossing (starting to sound familiar?) and sure enough just a bit further up the road, the alarm went off and the temp was at the wrong end of the scale. waited for half an hour but temp was still high. Checked under the bonnet and it seemed to me that here was no fluid in the top radiator hose (easy to squeeze with no resistance) eventhough the cooling system was filled just before I left to come home. Waited as long as I could and then nursed the vehicle home by driving and picking up speed and then switching motor off and coasting when the alarm went off. Finally made it home and hopped out to discover the fluid in the expansion tank was bubbling (along with with my blood pressure). :mad:
Has anyone had any similar problems or know what could possibly be the cause? Any ideas gratefully recieved and I will read them first thing in the morning but I really need to go and have that glass of wine now.

[PAT303]

The trouble first up I would say thermostat but you replaced it,it boiling for sure if the coolant is bubbling so that means the gauges are working,how soft-old are the rad hoses?,it is not happening all the time which means alot of the common faults like blocked core can be ruled out as they would cause the problem to happen regularly so a colapsed hose would be were I would start.Is the motor using coolant?. Pat

[justinc]

Where are the earth connections for the black box alarm? I have seen poor earthing in Defenders cause temp gauges to go right up into the red, when engine isn't actually hot. Did it feel like it was boiling? how much pressure was in the system? The top hose usually won't be full of coolant, expect it to be about half full as it is slightly higher than the coolant bottle. The bubbling may have just been because it was at operating temp. When it was getting hot, was the heater still working? and how is your viscous fan hub?

I am leaning toward an electrical fault still, try adding an extra earth lead from the battery neg to one of the seat box bolts, and see if it still does it.


Sorry for all the questions:D
JC

[clankilpatrick]

Gentlemen,
thankyou for the advice. I went out this morning and checked over a few things such as all of the hoses and belts (new less then a year ago) and also took out the new thermostat and put it and the old one into a pot of boiling water. The new one opened up but the old one is definately buggered. The earthing for the alarm system seems fine as well. The temp sender wire was recently covered in heat shrink and then put in split tubing as it had worn through and was effecting the temp gauge. My mechanic mate now thinks it may be the viscous fan thats causing the problem as the vehicle runs fine as long as I don't stop and let the motor go back to an idle. He thinks that the fan doesn't get back up to speed after i take off again and this is causing the motor to overheat. It seems to make sence to me as well. I am going to go for a run shortly and see if I can see a difference in the fan speed if I do stop for a bit after the motor has reached running temp. Any tips on definatively identifying if a viscous hub is had it or not?
cheers
dave

[clankilpatrick]

[QUOTE=justinc;1068300]Where are the earth connections for the black box alarm? I have seen poor earthing in Defenders cause temp gauges to go right up into the red, when engine isn't actually hot. Did it feel like it was boiling? how much pressure was in the system? The top hose usually won't be full of coolant, expect it to be about half full as it is slightly higher than the coolant bottle. The bubbling may have just been because it was at operating temp. When it was getting hot, was the heater still working? and how is your viscous fan hub?

I am leaning toward an electrical fault still, try adding an extra earth lead from the battery neg to one of the seat box bolts, and see if it still does it.


Sorry for all the questions:D
JC[/QUOTE

Gidday Justin,
Mate I have taken your advice from a previous post and put in an extra earth lead ages ago. I am pretty sure that the heater was working when I got home and it was definately bubbling in the expansion tank. Any suggestions on how I check the viscous fan hub would be gratefully received.
cheers
Dave

[slug_burner]

check this out http://www.aulro.com/afvb/technical-chatter/75136-td5-viscous-fan-coupling-stuffed.html#post935067, I too think there is something wrong with your viscous fan. The stop in traffic will stop the natural airflow and need the fan to pull the air through. When the viscous fan engages you will know it as it makes a bit of noise as it pulls one hell of a lot of air through. It sounds like a small plane .

although the thermostat not working is an issue that clouds the waters but given that replacing it did not solve the problem I will stick with the fan as the culprit.

Did you refill the cooling system through the plugs? could you have induced an airlock?

[clankilpatrick]

check this out http://www.aulro.com/afvb/technical-chatter/75136-td5-viscous-fan-coupling-stuffed.html#post935067, I too think there is something wrong with your viscous fan. The stop in traffic will stop the natural airflow and need the fan to pull the air through. When the viscous fan engages you will know it as it makes a bit of noise as it pulls one hell of a lot of air through. It sounds like a small plane .

although the thermostat not working is an issue that clouds the waters but given that replacing it did not solve the problem I will stick with the fan as the culprit.

Did you refill the cooling system through the plugs? could you have induced an airlock?

Gidday Slug burner,
mate I actually found your thread after I posted the last message and have just come back from a drive with the humble 2 inch paint brush. I stopped after 1km and used the brush to try and stop the fan and lo and behold it did. I then went for a longer drive staying in 4th gear to try and heat the motor up and stopped again and again the brush could stop the fan. I turned the vehicle off and waited for about 10 minutes and then took off to see if the vehicle would overheat but the temp needle stayed just left of centre all the way. I tried this a couple of times but of course Murphy's rules ensured thaqt the car stayed nice and cool and each time I could stop the fan with the brush using a moderate amount of pressure.
So, where to from here? I am guessing that if the viscous fan is properly engaged it would be unable to be stopped or at the very least extremely diffcult to stop, is this correct?
Yes I did fill the system through the thermostat plug, nice and steady and checked the level in the expansion tank a couple of times before I took off on the test drive. I am letting it cool down now and will check it again in an hour or so. mate I was trying to hear the noise you reckon the fan makes but with all the rattles the old truck makes now I can't even hear a passenger right next to me in the front seat let alone a fan in the engine bay.
cheers
Dave

[dullbird]

Have you tried removing the front grill when at temp and putting your hands on the radiator to see if there is differences in temp?

we had reoccuring problems with our 200tdi we changed everything still had it bled the system so many times...it ended up being our radiator that was pulled 6months before along with our disco radiator and neither of them had been rodded like we asked and paid for ...when the garage we took it to after cleaned the radiators they also said that not only was it blocked and had not been cleaned like suggested that a reasonable portion of the radiator was also starting to tire and brake down.

[PAT303]

Mate throw a falcon fan on it,straight bolt on fit and less than $50 from the wreckers.Buy the complete unit,they pump more air than LR units. Pat

[BilboBoggles]

Just one thing to note, the viscous fan uses the air temperature flowing through the radiator to vary it's lock up point. Now if you radiator is partially blocked, then it may be COLD at the center where the air flows through. In that case the viscous will not lock up.

If the radiator is fine and the viscous were working correctly, then you will definitely hear the roar of the fan as you increase the engine revs about 2000 RPM, if the engine is getting hot.

[slug_burner]

clankilpatrick,

I don't know that you would hear the fan inside the vehicle unless you had your window down and were cruising around at low speed. I have heard mine in the supermarket carpark, I doubt that you would hear it at road speed above all the other noises.

If your vehicle is not getting much above thermostat temperature the fan will not come on unless you idle it while stopped. If you idle the vehicle the fan should come on eventually, how long will depend on how hot the environment is.

PAT303,

Does the Falcon fan fit straight in? Don't you have to trim the blade tips?

[PAT303]

I've fitted two falcon fans to Tdi's and both went on with any trimming.Parking two vehicles nose to nose and feeling the air the falcon fan was blowing quite a bit more. Pat

[cewilson]

clankilpatrick,

I don't know that you would hear the fan inside the vehicle unless you had your window down and were cruising around at low speed. I have heard mine in the supermarket carpark, I doubt that you would hear it at road speed above all the other noises.

If your vehicle is not getting much above thermostat temperature the fan will not come on unless you idle it while stopped. If you idle the vehicle the fan should come on eventually, how long will depend on how hot the environment is.

PAT303,

Does the Falcon fan fit straight in? Don't you have to trim the blade tips?

I had to trim the fan blades for it to fit on my 200tDi - otherwise the blades hit the fan shroud. And if you don't trim them enough, they will hit on anything above a 25 degree slope :angel:

[wally]

I've fitted two falcon fans to Tdi's and both went on with any trimming.Parking two vehicles nose to nose and feeling the air the falcon fan was blowing quite a bit more. Pat

Pat, what model Falcon?

[PAT303]

EB falcon.They are a LH thread,you will recognise the nut when you see it.I don't know what the difference is between a 200 and 300 Tdi but I didn't modify a thing fitting them. Pat

[camel_landy]

Firstly... Do you actually have a problem???

As has already been noted, Defender electrics are notorious for making you think you're over heating when actually everything is fine.

See if you can borrow a laser thermometer, go for a drive and make it 'overheat'. As soon as it does, get the thermometer on it to confirm that the gauge is actually giving you a correct warning.

If it isn't, your problem is in the electrics.

If it is, the next step is to work out what is causing the problem.

Finally... Work out where the problem actually is rather than randomly replacing parts otherwise it's going to start costing $$$$

HTH

M

[clankilpatrick]

Eventhough its been awhile since I threw the post up and asked for some advice I thought I should let you all know how things turned out. I ended up buying a new viscous hub after trying every other possible avenue to sort out the overheating problems ie
1. new expansion tank cap
2. new thermostat
3. checking all eath connection and wiring to little black box and temp sender
4. checking all belts and hoses
5. cleaning out the radiator core with pressurised air etc
When I took the old hub off it was immediately obvious that there was lot of dirt and muck packed in around the centre of the hub. I tried to clean it out but it was well glued in as it looked like oil had been leaking from the hub and made a lovely sticky paste. I got onto it with the pressure cleaner and lo and behold once all the dirt was removed it was very obvious that the oil was leaking out of the centre. Only very slowly mind you. So the new hub went on and touchwood there seems to be no more overheating problems. Now just trying to see if the coolant levels change or there is water in the oil!!!! Hopefully no cracked head!!! One thing I have noticed is that the new expansion cap seems to hiss a fair bit when you turn off the motor after a fair run. I guess that its because its venting pressure. Maybe it's because I am paranoid about it and am keeping a close eye on the cooling system but I can't remember hearing the old cap doing this. Occasionally there is coolant leaking from around the cap as well but I am thinking that as the coolant:water ratio is all out of whack because of all the heating problems it is maybe boiling a bit ealier as there is more water in the mix. Hopefully a start from scratch and a new coolant change will sort this out.
Thanks for all of your help, ideas and input people
cheers
Dave

[slug_burner]

Hope all works out. I wouldn't go pouring new coolant into it until you sort out if you have a problem.

get a service place to sniff for products of combustion (gases in the cooling system)

[2stroke]

Blocked radiator? Can't see compressed air fixing that! The coolant makes 2 passes through the radiator and they can block easily... well that's what mine was when it was running hot when I bought it 6 1/2 years ago.